This invention relates generally to pulse detonation engines, and more particularly, to methods and apparatus for controlling air flow within a pulse detonation engine.
Known pulse detonation engines generally operate with a detonation process having a pressure rise, as compared to engines operating within a constant pressure deflagration. As such, pulse detonation engines may have the potential to operate at higher thermodynamic efficiencies than may generally be achieved with deflagration-based engines.
At least some known hybrid pulse detonation-turbine engines have replaced the steady flow constant pressure combustor within the engine with a pulse detonation combustor that may include at least one pulse detonation chamber. Although such engines vary in their implementation, a common feature amongst hybrid pulse detonation-turbine engines is that air flow from a compressor is directed into the pulse detonation chamber wherein the air is mixed with fuel and ignited to produce a combustion pressure wave. The combustion wave transitions into a detonation wave followed by combustion gases that are used to drive the turbine. However, known unvalved combustors are not designed to restrict backward traveling shock waves generated from the detonation wave and/or the reverse flow that follows the backward traveling shock wave and as such forward flow is reduced. Furthermore, because of asymmetries in the actual machined hardware or slight differences in geometry due to manufacturing, an amount of air flow entering each chamber may be different. Because known combustors are not designed to balance air flow through each chamber, the different amounts of air flow may adversely affect the combustor performance.
To facilitate enhancing combustor operations, at least some known pulse detonation engines include common air inlet plenums to facilitate restricting backward flow and balancing air flow. However, the use of plenums may still result in enough reverse flow and flow-imbalance to adversely affect combustion performance.